1. Field of the Invention
This invention relates to reversible electrical apparatus generally and, more particularly, to electrical apparatus which incorporate an audible alarm to alert the user that the electrical apparatus is in its reverse mode.
2. Background Art
While the present invention is described in some detail, for illustrative purposes, as being applied to a reversible DC power supply for electrochemical metallizing equipment to indicate when such power supply is in its reverse mode, it is within the intent of the present invention to encompass any application where it is desired to indicate, by audible means, when an electrical apparatus is in one of two modes. For example, the present invention may be incorporated into an reversible electric drill or similarly reversible electric tool, portable or stationary, to indicate when the drill is in reverse.
Electrochemical metallizing is a well known and useful technique for applying a surface deposit of any of a large number of metals or alloys to a base metal or alloy and comprises the bushing on of a plateable metal upon partial, selected areas of a metal or metallized part, usually an industrial component such as a tool, die, shaft, bearing, printing roll or similar machine part. Applications for electrochemical metallizing are found in a wide variety of industries, including aircraft, printing, materials handling, railroad, and printed circuits, for example. In many cases, the deposited and base metals are the same, especially when the component is one that is being repaired, although the metals may not necessarily be the same. The technique may also be used to place a solderable coating on metals that are not normally directly solderable. For example, a layer of nickel or copper may be placed by electrochemical metallizing on the surface of an aluminum component, after which that surface may be directly soldered using conventional soldering techniques. Equipment and materials for electrochemical metallizing processes are manufactured by Selectrons Ltd., Waterbury, Connecticut.
While electrochemical metallizing involves electrochemical deposition, it is not carried out in a conventional plating bath. Instead, the electrodeposit is swabbed or "painted" onto the surface to be coated. In appearance, electrochemical metallizing practice resembles arc welding more than electroplating. A cathodic cable from a special power supply is connected to the base metal. A second cable is connected anodically to the power supply and to any one of several working tools known as styluses comprising anodes of different sizes and shapes. The anodes are covered with an absorbent material, dipped into a plating solution (or the solution is flowed through or onto the anode), and the circuit completed by swabbing the wrapped anode over the area where metal build-up is desired. Electrochemical anodizing for etching or marking, for example, is accomplished in a similar fashion except that the current is reversed. The electrochemical metallizing equipment is very portable and obviates the need for sometimes large and heavy components to be moved to another location for repair, thus saving not only direct expense but also reducing downtime.
Normally in electrochemical metallizing there are three separate steps. In the first step, the base metal is cathodically connected to the power supply while the anodically connected stylus, which has been dipped in a cleaning solution, is used to electroclean the base metal to remove oils, dirt, etc. Then the current is reversed so that the stylus becomes the cathode and the base metal the anode, for scale and oxide removal and to activate the base metal. Following the latter step, the polarities are again reversed, returning them to the "forward" mode and metallizing proceeds as described above. A particular problem in the procedure is that the operator may neglect to effect the second reversal of polarities, thus leaving the base metal anodically connected to the power supply. The result of this is that metallizing cannot be accomplished and base metal starts to be lost, resulting in wasted time, at best, and in unsalvageable parts, at worst. While the power supplies used normally have lights to indicate in which mode the power supplies are set, the warning given by the lights is passive in that the operator must remember to check the lights before attempting to proceed with metallizing. Too frequently, the operator does not.
Accordingly, it is a principal object of the present invention to provide an audible alarm for reversible power supplies.
It is a further object of the invention to provide an audible alarm for reversible DC power supplies for electrochemical metallizing.
It is another object of the invention to provide such an alarm that is relatively inexpensive and easily incorporated into standard power supplies.
Other objects of the invention, as well as particular features and advantages thereof, will, in part, be obvious and will, in part, be apparent from the following description and the accompanying drawing figure.